Small Intestine Cancer: Types, Symptoms, and Risk Factors
Updated: 3 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Quick Answer: What is small intestine cancer?
Small intestine cancer, also called small bowel cancer, is a rare condition in which malignant cells develop in the small bowel, most commonly carcinoid tumors or adenocarcinomas. [1] Symptoms include abdominal pain, weight loss and bloody or black stool, but may be absent early. [1] Risk factors include older age and Crohn's or celiac disease. [1] Treatment often involves surgery. [1]
When to see a doctor
See a healthcare provider if you have abdominal pain that does not go away, unexplained weight loss, black or bloody stools, persistent nausea or vomiting, or yellowing of the skin or eyes. Get urgent medical care for severe abdominal pain with repeated vomiting or an inability to pass gas or stool, which can signal a bowel blockage. These symptoms have many causes, and most are not cancer, but they need to be evaluated.
What the research says
Small bowel tumors are rare, and more are being found. A 2023 review reports that small-bowel tumors make up about 0.6% of all new cancer cases in the US and about 3% of gastrointestinal neoplasms, across roughly 40 histological subtypes. Reported incidence has been rising, partly because of better diagnostic tools such as capsule endoscopy and enteroscopy (Vlachou et al., Best Practice & Research Clinical Gastroenterology, 2023) [2].
Many adenocarcinomas arise with a known predisposing condition. A review of small bowel adenocarcinoma found that almost 20% of cases are associated with Crohn's disease, Lynch syndrome, familial adenomatous polyposis, Peutz-Jeghers syndrome, or celiac disease. The duodenum is the most common site, and there is a slight male predominance (Aparicio et al., Cancers, 2022) [3].
Celiac disease was linked to a much higher risk. In the UK Biobank cohort of 478,753 adults, celiac disease was associated with a higher risk of small intestine cancer (hazard ratio 6.89; 95% CI, 2.18-21.75). The interval is wide because the cancer is rare, so the exact size of the risk is uncertain (He et al., JAMA Oncology, 2022) [4].
What Is Small Intestine Cancer?
Small intestine cancer occurs when malignant cells form in the tissues of the small bowel, the longest part of the digestive tract. The small intestine connects the stomach to the large intestine and carries out much of the work of digestion and nutrient absorption. It has three sections: the duodenum (the first part, next to the stomach), the jejunum (the middle section), and the ileum (the final and longest section). [1]
Although the small intestine makes up most of the length of the digestive tract, cancer here is rare. In the United States it accounts for only about 3% of gastrointestinal cancers, far fewer than cancers of the colon, rectum, esophagus, or stomach. [1] [2] Because it is uncommon and its symptoms are non-specific, it can be hard to diagnose early. There is also no standard screening test for the general population.
What are the types of small intestine cancer?
Small intestine cancers are classified by the type of cell where they start. Each type behaves differently and needs its own treatment approach.
Carcinoid (neuroendocrine) tumors: These start in neuroendocrine cells, which help produce hormones and regulate digestive juices. They account for a little less than half of cases and are often slow-growing and silent. [1] See our guide to gastrointestinal neuroendocrine tumors and to neuroendocrine tumors in general.
Adenocarcinomas: These begin in the glandular cells that line the inside of the small intestine and make up about one-third of cases. [1]
Sarcomas: These develop in connective tissue such as muscle. The most common form in the small intestine is the gastrointestinal stromal tumor (GIST). [1]
Lymphomas: These start in lymphocytes, a type of white blood cell in the immune system. [1]
Cancer type | Where it starts | Approximate share of cases |
|---|---|---|
Carcinoid (neuroendocrine) tumor | Neuroendocrine cells | A little less than half |
Adenocarcinoma | Glandular cells lining the intestine | About one-third |
Sarcoma (including GIST) | Connective tissue | Smaller share |
Lymphoma | Lymphocytes (immune cells) | Smaller share |
What are the symptoms of small intestine cancer, and how is it detected?
Symptoms vary with the tumor's type and location. Carcinoid tumors in particular are often silent and are found by chance during imaging for another reason. [1] When symptoms do appear, they may include abdominal pain or cramps, a lump in the abdomen, and unexplained weight loss. [1]
Other signs include persistent nausea, vomiting, or diarrhea. [1] Tumors that bleed can cause anemia (a low red blood cell count), which may make you feel tired or look pale. Jaundice (yellowing of the skin and eyes) and bloody or black stools can also occur. [1] Some carcinoid tumors release hormones that cause flushing of the skin, often with a purplish tint on the arms and upper body. [1]
What causes small intestine cancer, and who is at risk?
Small intestine cancer starts when genetic changes alter a cell's DNA so that it multiplies without control and forms a mass. [1] The reason for these changes is often unknown, but several risk factors have been identified.
Age: most cases are diagnosed in middle age or later. Cleveland Clinic gives an average age at diagnosis of about 65. [1]
Sex and ethnicity: it is slightly more common in men and, in the US, among Black individuals (with the exception of lymphoma). [1]
Chronic bowel inflammation: Crohn's disease and celiac disease raise the risk. [1] [3] [4]
Inherited syndromes: Lynch syndrome, familial adenomatous polyposis (FAP), and Peutz-Jeghers syndrome. [1] [3]
Weakened immune system: for example from HIV/AIDS, radiation therapy, or medicines used after an organ transplant. [1]
How is small intestine cancer diagnosed?
Because the condition is rare, diagnosis often takes several steps. Your provider will start with a physical exam and medical history. Blood tests help assess organ function and check a complete blood count (CBC) for anemia from tumor bleeding. [1]
Imaging and procedures are usually needed to confirm the diagnosis. An upper endoscopy can examine the duodenum, while capsule endoscopy or double-balloon enteroscopy can reach deeper into the small bowel. [1] [2] During endoscopy, the doctor can take a biopsy, a small tissue sample that a pathologist examines in the laboratory. [1] CT or MRI scans and barium X-rays help show the tumor's size and whether it has spread. [1]
Diagnostic tool | Function | Purpose |
|---|---|---|
Endoscopy and enteroscopy | Internal visual exam | Direct observation and biopsy |
Blood tests (CBC) | Cell count analysis | Detecting anemia or organ stress |
CT scan, MRI, or X-ray | Detailed body imaging | Locating tumors and checking for spread |
How is small intestine cancer treated, and what is the outlook?
Treatment is individualized and depends on the cancer type, its stage, and its location in the bowel. Surgery is the most common approach and aims to remove the primary tumor and any affected nearby tissue. [1] If the cancer has spread to other organs, such as the liver or lymph nodes, additional treatments may be needed, and the options differ by type. A multidisciplinary team, including surgeons, oncologists, gastroenterologists, pathologists, radiologists, and nutrition specialists, usually guides care.
The outlook depends on how early the cancer is found and on the cell type. [1] Some carcinoid tumors grow slowly, while other types can be more aggressive. Your care team can explain what to expect for your specific diagnosis and stage, and regular follow-up with imaging, endoscopy, and symptom review is an important part of long-term care.
Conclusion
Small intestine cancer is uncommon, and its vague symptoms can delay diagnosis. Knowing the main types, the risk factors, and the warning signs helps you seek evaluation sooner. Modern tools such as capsule endoscopy, enteroscopy, and cross-sectional imaging have improved how these tumors are found, and care from a multidisciplinary team gives each person the best chance of a good outcome.
What are the next steps after a small intestine cancer diagnosis?
If you have persistent abdominal pain, unexplained weight loss, black or bloody stools, or you have Crohn's disease, celiac disease, or a family history of an inherited bowel cancer syndrome, talk to your healthcare provider about the right evaluation for you.
Trusted resources: Cleveland Clinic: Small Intestine Cancer, American Cancer Society: Small Intestine Cancer, National Cancer Institute: Small Intestine Cancer Treatment (PDQ)
Frequently Asked Questions
How rare is small intestine cancer?
Very rare. Small-bowel tumors make up about 0.6% of new cancer cases in the US and roughly 3% of gastrointestinal cancers.
What are the three parts of the small intestine?
The duodenum (the start, next to the stomach), the jejunum (the middle), and the ileum (the end).
Which part of the small intestine is most likely to develop cancer?
It depends on the type. Adenocarcinomas most often arise in the duodenum, while carcinoid (neuroendocrine) tumors tend to be found in the lower small intestine, including the ileum.
What is a carcinoid tumor?
A carcinoid tumor is a type of neuroendocrine tumor that starts in neuroendocrine cells, which produce hormones and help regulate digestion. Many grow slowly.
Can small intestine cancer cause no symptoms?
Yes. Many tumors, especially carcinoid tumors, cause no symptoms and are found by chance during tests for another reason.
What are the most common symptoms?
Abdominal pain or cramps, unexplained weight loss, nausea, vomiting, diarrhea, anemia, and bloody or black stools.
Does celiac disease increase the risk?
Yes. Celiac disease and Crohn's disease are recognized risk factors. In a large UK cohort, celiac disease was linked to a markedly higher risk of small intestine cancer, although the cancer remains rare overall.
What is the average age at diagnosis?
Cleveland Clinic gives an average age of about 65 at diagnosis.
How is a biopsy performed in the small intestine?
A biopsy is usually taken during an endoscopy, using small instruments passed through the scope to remove a tissue sample for laboratory analysis.
What is a GIST?
GIST stands for gastrointestinal stromal tumor, a type of sarcoma that starts in the connective tissue of the digestive tract.
Can small intestine cancer spread to other organs?
Yes. Cancer cells can spread through the blood or lymph nodes to other parts of the body, such as the liver. This is called metastasis.
Why is anemia a symptom of this cancer?
Tumors in the small intestine can bleed slowly, causing a gradual loss of red blood cells and leading to anemia.
What is a double-balloon enteroscopy?
A double-balloon enteroscopy is a specialized endoscopy that uses balloons to help the scope move deeper into the small intestine than a standard endoscope can reach.
Is small intestine cancer more common in men or women?
Small intestine cancer is slightly more common in men than in women.
Can inherited genetics play a role?
Yes. Inherited syndromes such as Lynch syndrome, familial adenomatous polyposis (FAP), and Peutz-Jeghers syndrome increase the risk.
References
Cleveland Clinic. Small Intestine Cancer: Symptoms, Causes, Prognosis & Treatment. Cleveland Clinic. May 9, 2022. https://my.clevelandclinic.org/health/diseases/6225-small-intestine-cancer
Vlachou E, Koffas A, Toumpanakis C, et al. Updates in the diagnosis and management of small-bowel tumors. Best Pract Res Clin Gastroenterol. 2023;64-65:101860. PMID 37652650. https://doi.org/10.1016/j.bpg.2023.101860
Aparicio T, Pachev A, Laurent-Puig P, et al. Epidemiology, risk factors and diagnosis of small bowel adenocarcinoma. Cancers (Basel). 2022;14(9):2268. PMID 35565398. https://doi.org/10.3390/cancers14092268
He MM, Lo CH, Wang K, et al. Immune-mediated diseases associated with cancer risks. JAMA Oncol. 2022;8(2):209-219. PMID 34854871. https://doi.org/10.1001/jamaoncol.2021.5680
Medical Disclaimer
This article is for informational purposes only and does not constitute medical advice. Always seek the advice of a qualified healthcare professional with any questions you may have regarding a cancer diagnosis or gastrointestinal symptoms.
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